The objectives of this project are (1) to assess the efficacy of a specific four-level treatment protocol designed to achieve functional lexical retrieval in aphasic patients, (2) to assess the relative efficacies of two levels of treatment intensity, and (3) to identify patient characteristics which may predict favorable response to the treatment. Subjects' acquisition rates for noun and verb stimuli undergoing treatment will be compared with those for stimuli which are only presented for naming without direct intervention or corrective feedback during treatment sessions. Response generalization to untreated stimuli and stimulus generalization to successive levels of the treatment protocol and to a referential communication task will also be assessed. Stimuli from different semantic categories will be treated on once-per-day and twice-per-day bases to allow assessment of the relative efficacies of these two levels of treatment intensity. Examination of subjects' linguistic impairment profiles and analyses of covariance, with measures of overall severity of aphasia, naming performance, and auditory-word-to-picture matching performance as covariates, will be used to identify patient characteristics which may predict favorable response to the treatment. The results of this study will potentially enhance the provision of language rehabilitation to aphasic patients by providing information about which patients may benefit from specific lexical retrieval treatment provided in two different amounts. This information should yield long-term benefits for both individual patient's recovery of functional verbal expression and service delivery planning in aphasia rehabilitation.